Electrode ink for water electrolysis, water electrolysis electrode comprising same and membrane electrode assembly for water electrolysis

Abstract

Electrode ink for water electrolysis, of the present invention, comprises a metal-supported catalyst, carbon nanotubes, and an ionomer, and includes 0.01-3 wt% (based on solids) of carbon nanotubes.

Description

Water electrolysis electrode ink, a water electrolysis electrode including the same, and a membrane electrode assembly for water electrolysis

[0001] The present invention relates to a water electrolysis electrode ink, a water electrolysis electrode containing the same, and a membrane electrode assembly for water electrolysis. More specifically, the present invention relates to a water electrolysis electrode ink having excellent electrical conductivity, anion exchange membrane water electrolysis performance and durability, and improved coating properties and surface characteristics, a water electrolysis electrode containing the same, and a membrane electrode assembly for water electrolysis.

[0002] In the current climate where the development of eco-friendly fuels is a major topic, water electrolysis is the only commercially available technology capable of producing the most perfectly green hydrogen. Water electrolysis technology is divided into three types: Proton Exchange Membrane Electrolysis Cell (PEMEC), Alkaline Electrolysis Cell (AEC), and Solid Oxide Electrolysis Cell (SOEC). As AEC has a history spanning over 100 years, it is a mature field in both market and technology; consequently, it is difficult to expect significant reductions in equipment production and operating costs through technological development. Furthermore, due to the low hydrogen production density of AEC, producing large volumes of hydrogen inevitably requires scaling up production and consequently increasing the size of equipment, making it difficult to ensure economic viability. PEMEC is a relatively recently commercialized technology that can directly produce high-purity, high-pressure hydrogen in compact facilities, and offers significant potential for reducing production and operating costs through technological development. However, as this is a recently commercialized technology, long-term operating data has not been secured, making it difficult to guarantee stability. Furthermore, the cost and processing expenses of the separator (or bipolar plate) materials, which are inevitably required under acidic operating conditions, account for a significant portion of production costs and can act as a burden. SOEC has the unique advantage of being usable as either an electrolyzer or a fuel cell with the same configuration, depending on the operating method. However, there are limitations: the solid oxide catalyst is susceptible to physical shock, limiting its stable application to stationary facilities; and the extremely high temperature of the water used in the process necessitates installation near sites where ultra-high temperature water is generated, such as steel mills or nuclear power plants.

[0003] Accordingly, anion exchange membrane electrolysis (AEMEC) is being proposed as an alternative to solve the problems of existing water electrolysis methods. AEMEC has the advantage of enabling high-density hydrogen production similar to the hydrogen production density of PEMEC, resulting in a small facility size, and low production costs because it utilizes AEC materials.

[0004] Conventionally, catalysts primarily used in water electrolysis electrode layers consisted of metals supported on spherical carbon supports. However, such catalysts suffer from poor electrical conductivity due to high interfacial resistance between the materials. Additionally, an increase in solid content during the ink manufacturing stage leads to coating film defects, while a decrease in solid content results in reduced coating performance due to low viscosity.

[0005] Therefore, there is a need to develop an electrode ink that can reduce interfacial resistance during electrical conduction, improve AEMWE performance, exhibit excellent coating properties without the addition of conventional solids, and possess superior surface characteristics and film strength of the coating film.

[0006] Related prior art is KR 10-2018-0121004.

[0007] The objective of the present invention is to provide a water electrolysis electrode ink capable of increasing the electrical conductivity of the electrode coating layer.

[0008] Another objective of the present invention is to provide a water electrolysis electrode ink capable of improving the performance of AEMWE by reducing interfacial resistance.

[0009] Another objective of the present invention is to provide a water electrolysis electrode ink with improved coating properties by controlling the rheology of the ink.

[0010] Another objective of the present invention is to provide a water electrolysis electrode ink capable of improving the electrode layer coating film and enhancing film strength by strengthening the interaction between solid components.

[0011] Another objective of the present invention is to provide a water electrolysis electrode ink capable of improving the surface condition of an electrode coating film.

[0012] Another objective of the present invention is to provide a water electrolysis electrode comprising the above-mentioned water electrolysis electrode ink and a membrane electrode assembly for water electrolysis using the same.

[0013] The above and other objectives of the present invention can all be achieved by the present invention described below.

[0014] 1. One aspect of the present invention relates to a water electrolysis electrode ink. The water electrolysis electrode ink comprises a metal-supported catalyst; carbon nanotubes; and an ionomer; and comprises 0.01 to 3 weight% (based on solid content) of carbon nanotubes.

[0015] 2. In the above embodiment 1, the metal-supported catalyst is a catalyst in which a metal is supported on a carbon support, and the metal may include one or more selected from platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), rhodium (Rh), gold (Au), silver (Ag), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), chromium (Cr), manganese (Mn), molybdenum (Mo), yttrium (Y), and combinations thereof.

[0016] 3. In the above 1 to 2 embodiments, the carbon carrier may be spherical.

[0017] 4. In the above 1 to 3 embodiments, the carbon nanotube may have an aspect ratio (length / diameter) of 100 or more.

[0018] 5. In the above 1 to 4 embodiments, the electrode ink may comprise 100 parts by weight of a metal-supported catalyst, 0.01 to 3 parts by weight of carbon nanotubes; and 5 to 100 parts by weight of an ionomer.

[0019] 6. In the above 1 to 5 embodiments, the electrode ink may have a viscosity of 50 cPs to 10,000 cPs at 25°C.

[0020] 7. Another aspect of the present invention relates to a water electrolysis electrode. The water electrolysis electrode comprises the water electrolysis electrode ink of embodiments 1 to 6.

[0021] 8. In the above 7 embodiments, the electrode may have an electrical conductivity of 1 S / cm² to 10 S / cm² as measured by a 4-point probe device.

[0022] 9. Another aspect of the present invention relates to a membrane electrode assembly for water electrolysis. The membrane electrode assembly for water electrolysis comprises an electrolyte membrane; and an electrode layer formed on the surface of the electrolyte membrane; wherein the electrode layer is formed from the water electrolysis electrode ink of 1 to 6 embodiments.

[0023] 10. In the above 9 embodiments, the haze of the electrode layer may be 95% to 100%.

[0024] The present invention has the effects of providing a water electrolysis electrode ink capable of increasing the electrical conductivity of the electrode coating layer, improving the performance of the AEMWE by reducing interfacial resistance, improving coating properties by controlling the rheology of the ink, improving the electrode layer coating film by strengthening the interaction between solid components, enhancing film strength, and improving the surface condition of the electrode coating film, a water electrolysis electrode including the same, and a membrane electrode assembly for water electrolysis using the same.

[0025] Figure 1 shows the JV performance curves of the membrane electrode assemblies prepared in Example 1 and Comparative Example 2.

[0026] The present invention will be described in more detail below. Where terms such as 'comprising,' 'having,' and 'consisting of' are used in this specification, other parts may be added unless 'only' is used. Where a component is expressed in the singular, it includes cases where it includes the plural unless specifically stated otherwise.

[0027] In interpreting the components, they are interpreted to include a margin of error even in the absence of a separate explicit statement.

[0028] The water electrolysis electrode ink according to the present invention will be described in detail below.

[0029]

[0030] Water electrolysis electrode ink

[0031] The water electrolysis electrode ink of the present invention comprises a metal-supported catalyst; carbon nanotubes; and an ionomer; and comprises 0.01 to 3 weight% of carbon nanotubes (based on solid content).

[0032] (a) Metal-supported catalyst

[0033] The above metal-supported catalyst is a catalyst in which a metal is supported on a carbon support.

[0034] The above metal may include one or more selected from platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), rhodium (Rh), gold (Au), silver (Ag), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), chromium (Cr), manganese (Mn), molybdenum (Mo), yttrium (Y), and combinations thereof. The supported catalyst may be in the form of a single metal supported or two or more metals supported. Alternatively, two or more metals may be supported in the form of an alloy.

[0035] The carbon carrier may be spherical. In a specific example, carbon black, activated carbon, graphite, etc. may be used. In a specific example, the carbon carrier may have a BET of 30 to 1000 m² / g. For example, the carbon carrier may have a BET of 50 to 800 m² / g.

[0036] The metal-supported catalyst may have an average diameter (D50) of 10 nm to 1000 nm. For example, the metal-supported catalyst may have an average diameter (D50) of 20 nm to 800 nm.

[0037]

[0038] (b) Carbon nanotubes

[0039] The above carbon nanotubes may have an aspect ratio (length / diameter) of 100 or more, and in specific examples, 500 to 20,000. For example, it may be 700 to 18,000 or 800 to 17,000. Within the above range, interfacial resistance can be reduced, coating properties are excellent, the performance of AEMWE is improved, and electrode surface characteristics are excellent.

[0040] The above carbon nanotubes are 0.01 to 3 weight percent (based on solid content) of the water electrolysis electrode ink. If it is less than 0.01 weight percent, there is no significant effect, and if it exceeds 3 weight percent, there is a disadvantage that the ink cannot be manufactured due to high viscosity.

[0041] In addition, the carbon nanotubes are included in an amount of 0.01 to 3 parts by weight, 0.05 to 2 parts by weight in specific examples, and preferably 0.1 to 1.5 parts by weight, per 100 parts by weight of the metal-supported catalyst. Within this range, electrical conductivity is excellent and roll coating suitability can be increased.

[0042]

[0043] (c) Ionomer

[0044] The above ionomer may be a perfluorinated ionomer, a partially fluorinated ionomer, or a hydrocarbon ionomer, but is not necessarily limited thereto. Examples include polyperfluorosulfonic acid, polyperfluorocarboxylic acid, a copolymer of tetrafluoroethylene and fluorovinyl ether containing a sulfonic acid group, PTFE-g-TFS, PVDF-g-PSSA, polysulfonated imide, etc.

[0045] The above ionomer may be included in an amount of 5 to 100 parts by weight, or 10 to 70 parts by weight in specific examples, per 100 parts by weight of the metal-supported catalyst. For example, it may be included in an amount of 12 to 68 parts by weight, or 15 to 65 parts by weight.

[0046]

[0047] The water electrolysis electrode ink of the present invention may further include a solvent and other conventional additives in addition to the above components.

[0048] In a specific example, the solvent may be water, alcohol, acetone, ethylene carbonate, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), etc., but is not necessarily limited thereto. For example, water, alcohol, etc. may be used. The alcohol may include monohydric or dihydric alcohols. In a specific example, it may be distilled water, ethyl alcohol, methyl alcohol, or isopropyl alcohol. The solvent may be included in an amount of 0.1 to 40 weight% of the total electrode ink. For example, it may be included in an amount of 1 to 35 weight%.

[0049] The above additives include viscosity modifiers, leveling agents, etc., and may be included in an amount of 0.1 to 5 weight percent of the total electrode ink. For example, they may be included in an amount of 0.5 to 4.5 weight percent.

[0050]

[0051] The water electrolysis electrode ink of the present invention can be prepared by mixing a metal-supported catalyst, carbon nanotubes, an ionomer, and optionally other additive components.

[0052] The above-mentioned water electrolysis electrode ink may have a viscosity of 50 cPs to 10,000 cPs at 25°C. In this range, excellent coating properties can be exhibited, and the surface characteristics of the electrode are excellent. In a specific embodiment, the viscosity (at 25°C) of the above-mentioned water electrolysis electrode ink may be 100 to 5,000 cPs. For example, it may be 150 to 4,800 cPs.

[0053]

[0054] Water electrolysis electrode and membrane electrode assembly

[0055] Another aspect of the present invention relates to a water electrolysis electrode. The water electrolysis electrode may be formed by including the water electrolysis electrode ink described above.

[0056] In one embodiment, the electrode may be formed by coating and drying the water electrolysis electrode ink. The coating may be spray coating, bar coating, doctor blade, roll-to-roll coil, impregnation coating, gravure coating, slot die coating, lip coating, etc., but is not necessarily limited thereto.

[0057] The water electrolysis electrode formed from the water electrolysis electrode ink of the present invention may have an electrical conductivity of 1 S / cm² or more and 10 S / cm² or less, as measured by a 4-point probe device, and in a specific example, 1.5 to 10 S / cm². For example, 2 to 9 S / cm 2 It could be.

[0058] Another aspect of the present invention relates to a membrane electrode assembly for water electrolysis. The membrane electrode assembly for water electrolysis comprises an electrolyte membrane; and an electrode layer formed on the surface of the electrolyte membrane; wherein the electrode layer is formed from the water electrolysis electrode ink.

[0059] The above electrolyte membrane may preferably be an anion exchange membrane.

[0060] The above electrode layer can be directly coated on one surface of the electrolyte membrane, or an electrode layer can be formed by coating on a polymer film and then transferring it to the electrolyte membrane to bond it.

[0061] In a specific example, the light transmittance of the electrode layer may be 95% to 100%, 97.5% to 100%, for example 99% to 100%.

[0062]

[0063] The present invention is to be explained more specifically below through examples and comparative examples; however, these examples are for illustrative purposes only and should not be interpreted as limiting the invention.

[0064]

[0065] Examples

[0066] The specifications of each component used below are as follows:

[0067] (1) Metal-supported catalyst: Sigma Aldrich Platinum-on-Carbon catalyst (Product name: 205958) was used.

[0068] (2) Ionomer: An ionomer manufactured by Fumatech (product name: FAA-3-SOULT-10) was used.

[0069] (3) Carbon nanotubes: Self-manufactured carbon nanotubes with an aspect ratio of 1,000 to 10,000 were used.

[0070] (4) Solvent: 200 parts by weight of distilled water, 300 parts by weight of ethyl alcohol, 450 parts by weight of methyl alcohol, and 50 parts by weight of isopropyl alcohol were mixed and used.

[0071]

[0072] Example 1

[0073] Electrode ink was prepared by mixing each of the above components according to the composition in Table 1. After evaluating the physical properties of the prepared ink by the following method, a membrane electrode assembly was fabricated by coating it using the CCM (Catalyst coated membrane) method.

[0074]

[0075] Comparative Example 1

[0076] The procedure was performed in the same manner as Example 1 above, except that the carbon nanotube (a) content was changed.

[0077]

[0078] Comparative Example 2

[0079] The procedure was performed in the same manner as Example 1 above, except that carbon nanotubes were not added.

[0080]

[0081] Comparative Example 3

[0082] The procedure was carried out in the same manner as Example 1 above, except that carbon nanotubes were applied as a carbon carrier instead of being separately added. It was impossible to manufacture it into ink due to poor dispersion.

[0083]

[0084] The physical properties of the fabricated membrane electrode assembly were evaluated, and the results are shown in Table 1.

[0085] In addition, the JV performance of the fabricated membrane electrode assembly was evaluated and is shown in Figure 1.

[0086] Example 1 Comparative Example 1 Comparative Example 2 Supported Catalyst 100 100 100 Ionomer 20 20 20 Carbon Nanotube 0.250 Solvent 1000 1000 1000 Viscosity 200 40,000 100 Particle Size (D50) 71 nm 580 nm 64 nm Coating Properties Good Poor Good Electrical Conductivity 2.1 S / cm 2 -1.9 S / cm 2 Haze 99.7% 90.0% 98.5%

[0087] The unit of content is by weight.

[0088]

[0089] Physical property evaluation method

[0090]

[0091] (1) Viscosity (cPs): Measured with spindle 18 on a Brookfield LV viscometer.

[0092] (2) Particle size (nm): Particle size is measured using a Malvern particle size analyzer.

[0093] (3) Coating properties: Check the occurrence and extent of cracks through bar coating.

[0094] (4) Conductivity (S / cm2): Area conductivity is measured using a 4-point probe.

[0095] (5) Haze (%): Measure light transmittance using a haze meter and subtract from 100%.

[0096]

[0097] As shown in Table 1 above, Example 1, which uses the electrode ink of the present invention, exhibits excellent coating properties, and it can be confirmed that the electrode coated with it has excellent conductivity. Comparative Example 1, in which carbon nanotubes were applied beyond the scope of the present invention, had poor suitability for the dispersion process due to the excessive viscosity of the ink, resulting in poor ink quality and making it impossible to fabricate a membrane electrode assembly. Comparative Example 2, which did not use carbon nanotubes, also had good ink quality, but compared to Example 1, it had lower viscosity, resulting in poor suitability for roll coating, and also had low haze and electrical conductivity.

[0098] In addition, as shown in FIG. 1, Example 1, which applied the electrode ink of the present invention, exhibits an excellent performance curve. Comparative Example 1, in which carbon nanotubes were applied beyond the scope of the present invention, could not fabricate a membrane electrode assembly due to electrode coating defects, making performance measurement impossible. Comparative Example 2, which did not use carbon nanotubes, showed a lower performance curve than Example 1.

[0099]

[0100] Simple variations or modifications of the present invention can be easily implemented by those skilled in the art, and all such variations or modifications are considered to be within the scope of the present invention.

Claims

1. Metal-supported catalyst; Carbon nanotubes; and Ionomer; It is an electrode ink containing, The above electrode ink is a water electrolysis electrode ink containing 0.01 to 3 weight% (based on solid content) of carbon nanotubes.

2. In Paragraph 1, The above metal-supported catalyst is a catalyst in which a metal is supported on a carbon support, and A water electrolysis electrode ink comprising one or more metals selected from platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), rhodium (Rh), gold (Au), silver (Ag), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), chromium (Cr), manganese (Mn), molybdenum (Mo), yttrium (Y), and combinations thereof.

3. In Paragraph 2, The above carbon carrier is spherical, and the water electrolysis electrode ink.

4. In Paragraph 1, The above carbon nanotubes are a water electrolysis electrode ink having an aspect ratio (length / diameter) of 100 or more.

5. In Paragraph 1, The above electrode ink comprises 100 parts by weight of a metal-supported catalyst, 0.01 to 3 parts by weight of carbon nanotubes; and 5 to 100 parts by weight of an ionomer, for water electrolysis electrode ink.

6. In Paragraph 1, The above electrode ink is a water electrolysis electrode ink having a viscosity of 50 cPs to 10,000 cPs at 25°C.

7. A water electrolysis electrode comprising the water electrolysis electrode ink of any one of claims 1 to 6.

8. In Paragraph 8, The above electrode is a water electrolysis electrode having an electrical conductivity of 1 to 10 S / cm2 as measured by a 4-point probe device.

9. Electrolyte membrane; and Includes an electrode layer formed on the surface of the above electrolyte membrane; A membrane electrode assembly for water electrolysis, wherein the electrode layer is formed from the water electrolysis electrode ink of any one of claims 1 to 6.

10. In claim 9, the electrode layer is a membrane electrode assembly for water electrolysis having a haze of 95% to 100%.

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